Crimp *and* solder a crimp connector? Good? Bad? Why?

[coppice]

I've been crimping AWG16 into female pins and then soldering them for 4 years in a product and have never had any fail.
The connector is the same kind as computer ATX plugs, just less pins

If the joints are not flexed or vibrated in service you'll usually get away with doing that, especially if you took some action to minimise wicking during the soldering. That doesn't make it a preferred solution.

[coppice]

Another thread has some valuable input to the topic.
https://www.ericthecarguy.com/kunena/9-ETCG-Suggestion-Box/52531-solder-vs-crimp

quote:

"I work in the aerospace industry (think launchpads, not runways) and we use crimps and soldered joints fairly interchangeably. Initial assembly and bench-work is typically soldered. Yet while making repairs or modifications on the spacecraft, we use crimp connections almost exclusively. This is because it's easy to reproduce a functional joint in difficult to reach places, or from uncomfortable working positions.

The crimpers I use at work span many brands and are routinely calibrated by our in house metrology lab."

Few posts above I was told that small crimp connectors should be more easily made gas tight because of small area right, metals should fuse together etc.
Now to verify this I took a bunch of factory crimped (with proper tools I suppose) connectors from computers and a scalpel, I dissembled the connectors without much effort, the strands were not fused together or to the connector. It's actually strange that wires pull out so easy once you know how to release them.

The guy being quoted implies he either works in missiles or space vehicles. In both those cases the vibration levels are phenomenal. So much so that lots of materials can't be used for insulation because the vibration liquifies them. The first lesson you learn in soldering is you should always avoid using solder for structural purposes. In high vibration environments you have to take this policy to an extreme. Everything has to be pretty tight and solid before any solder is applied. Solder is so soft and low melting point that it can liquify under high vibration if there is any significant thickness of solder between the mating parts. Every electrical joint, and piece of insulation, is considered with great care in missiles. Anything without a proven track record is generally prohibited, and needs to build a track record outside actual missiles. There are no joint types which are freely interchanged.

[tooki]

My understanding is that adding solder to a good crimp basically gives you all the disadvantages of both, and negates their respective advantages, making it a big no-no. I think that often, people are adding solder to a bad crimp and seeing an improvement, which may be the case, but that’s because it’s a bad crimp. If you can’t get good crimps, then you should just forget the crimping altogether and use connectors with solder cups or lugs instead.

[coppice]

My understanding is that adding solder to a good crimp basically gives you all the disadvantages of both, and negates their respective advantages, making it a big no-no. I think that often, people are adding solder to a bad crimp and seeing an improvement, which may be the case, but that’s because it’s a bad crimp. If you can’t get good crimps, then you should just forget the crimping altogether and use connectors with solder cups or lugs instead.

If you have crimped properly, solder can't get into the actual crimped area, so it can't affect the actual crimp. The main problem with soldering after crimping is wicking. Most crimping is of multi-strand wires. Solder is drawn between the strands for a considerable distance, just as wax is drawn up a candle wick. Where that solder ends you have a point where often just a few wiggles of the wire will cause a fracture. So, the solder wrecks the benefits of crimping, but crimping doesn't have any drawbacks compared to solder, unless you have a poor crimping technique which you can't rely on.

[Psi]

I've been crimping AWG16 into female pins and then soldering them for 4 years in a product and have never had any fail.
The connector is the same kind as computer ATX plugs, just less pins

If the joints are not flexed or vibrated in service you'll usually get away with doing that, especially if you took some action to minimise wicking during the soldering. That doesn't make it a preferred solution.

yeah, just a touch of solder, i don't let it wick up past the insulation crimp

[wraper]

I've been crimping AWG16 into female pins and then soldering them for 4 years in a product and have never had any fail.
The connector is the same kind as computer ATX plugs, just less pins

If the joints are not flexed or vibrated in service you'll usually get away with doing that, especially if you took some action to minimise wicking during the soldering. That doesn't make it a preferred solution.

yeah, just a touch of solder, i don't let it wick up past the insulation crimp

Do you value your time at least a little bit? Wasting additional time on modifying connections from standard to substandard does not make much sense.

[Siwastaja]

That makes a lot of sense when you are unsure about the successfullness of your crimps due to a cheap crimp tool or lack of experience using it.

Substandard crimps are a total catastrophe, and soldering makes it much better - although if the crimp is done correctly, then the solder indeed is a downgrade. But for someone experienced with soldering, this gives more consistency if they can accept the robustness of the soldered connection.

"The right way to do it" would of course to get the proper crimp tools and do some quality control on the crimps. But many people who are experienced in electronics - i.e., do all their work soldering - are often unsure about that.

[wraper]

That makes a lot of sense when you are unsure about the successfullness of your crimps due to a cheap crimp tool or lack of experience using it.

Substandard crimps are a total catastrophe, and soldering makes it much better - although if the crimp is done correctly, then the solder indeed is a downgrade. But for someone experienced with soldering, this gives more consistency if they can accept the robustness of the soldered connection.

"The right way to do it" would of course to get the proper crimp tools and do some quality control on the crimps. But many people who are experienced in electronics - i.e., do all their work soldering - are often unsure about that.

He wrote it was a product made for 4 years, so no, it does not make sense. Supposedly it should be commercial product so there is no problem getting proper crimping tool for the task.

I've been crimping AWG16 into female pins and then soldering them for 4 years in a product and have never had any fail.
The connector is the same kind as computer ATX plugs, just less pins

[Psi]

That makes a lot of sense when you are unsure about the successfullness of your crimps due to a cheap crimp tool or lack of experience using it.

Substandard crimps are a total catastrophe, and soldering makes it much better - although if the crimp is done correctly, then the solder indeed is a downgrade. But for someone experienced with soldering, this gives more consistency if they can accept the robustness of the soldered connection.

"The right way to do it" would of course to get the proper crimp tools and do some quality control on the crimps. But many people who are experienced in electronics - i.e., do all their work soldering - are often unsure about that.

He wrote it was a product made for 4 years, so no, it does not make sense. Supposedly it should be commercial product so there is no problem getting proper crimping tool for the task.

I've been crimping AWG16 into female pins and then soldering them for 4 years in a product and have never had any fail.
The connector is the same kind as computer ATX plugs, just less pins

Yes there is, i'm not made of money, the official crimp tool is  US$1200 and i think you still have to buy the crimp insert for the pin you want to crimp.
Instead, I'm using a $60 aftermarket crimp tool designed for the type of pin i'm crimping.
works fine as far as i can tell.

I don't think i will ever trust crimped connections. The only way to know if the crimp is good is to pull on the cable hard and see if it comes out.  But if i do that i definitely wont trust the crimp after that.
So i always drop some solder into the crimp under the microscope for the high current crimps.
The other low current crimps i dont bother.
There's often 10A continuous flowing through the high current connections so i sleep better at night knowing they were also soldered and are not going to develop a high resistance that will cause them to melt the connector.

I'd rather they break off clean from vibration than catch on fire.

[smile]

Now knipex own video shows this crimp quality or the lack of it:



As you can see there is empty space between wires, this is with KNIPEX Hex Self-Adjusting Crimping Pliers for end sleeves (ferrules) with lateral access (97 53 14)

If Hex plier crimp like this then square ones are even worse (because you have to match the wires not only by AWG but make sure manufacturer does not lie about it.), and I don't get why KNIPEX does not have same design Hex crimp pliers as they have way more robust ones

[nctnico]

Ferrules don't need much crimping because they end up under a screw anyway.

[wraper]

Now knipex own video shows this crimp quality or the lack of it:

I rather see your imagination at work, adding what cannot be seen. Sees the gaps between strands  . First of all, picture is not clear enough. Secondly, strands cannot be of exactly of the same length, and there won't be completely tight crimp on the open end because of this. To see if it's tight or not, you would need to cut the crimp and see what's inside. Also it looks like those strands stick a little bit outside of ferrule as it often is done. BTW ferrules usually are not crimped as a one flat piece.

[coppice]

... To see if it's tight or not, you would need to cut the crimp and see what's inside. Also it looks like those strands stick a little bit outside of ferrule as it often is done. BTW ferrules usually are not crimped as a one flat piece.

Isn't it almost universal with crimps that either you can't see the end of the wire (e.g. BNC centre pins) or the wires are neatly trimmed to extend beyond the ferrule, as is the case with the Knipex image shown above?

In pretty much all cases the crimp stops a little short of each end of the ferrule, on purpose. This avoids an abrupt transition from crimped to non-crimped areas on the multi-strand wire, which would increase stresses as the flexible wire is wiggled.

You only get to see the actual crimp quality by a good clean cut through the middle of the ferrule, taking care not to let the cutting tool smear the soft metals together.

[Vernichtung]

I have spent the last 10 years in the Automotive industry and I personally use both, whist crimp is the most common There are situation in which I wouldn't settle for anything less than a soldered connection.
For example I will always crimp AND then solder (to the crimp terminal) a ring terminal. I find this helps to ensure that corrosion is rarely an issue. 

[expinkolator]

Now knipex own video shows this crimp quality or the lack of it:

Bootlace ferrules are not crimp connections, they are crimped to keep them on the wire. The tools are not intended and don't have the strength to deform the wire strands into a single gas tight mass, the thin walls of the ferrule don't have the strength to hold them together anyway.

The are used to make sticking the wire in a hole easier the same as real bootlaces, to provide a bit of mechanical strength, and for cosmetic reasons.

You don't have anything to argue about.

An interesting question is are they good to use with spring (or cage) clamp type terminals. I suspect not.

[Fraser]

If you want to see a scary video filled with bad ideas and practices, take a look here......

https://youtu.be/v2OvuvCuWsk

When working on vessels that navigate water you need to do electrical connections properly and use the correct parts for the job. Flattening a copper pipe to create a crimp lug may work for emergency 'Bush Engineering' but it isn't the best idea for mission critical wiring that can fail at the most inconvenient time.

I like the Dangar Marine video's but this one made me spit my coffee when I saw his ideas about tinning the cable before crimping. Total botch cable by the end of the video. If I had made such at Maritime technical college I would have been laughed out of the room, and rightly so.

Fraser

[smile]

Ferrules don't need much crimping because they end up under a screw anyway.

And you don't use then in wago 221 spring loaded terminals? Inserting stranded wire is a mess. You should be able to save one slot by crimping say two 2.5mm2 wires together into one crimp and using single port on wago 221.

Is that bad practice too, then I don't understand crimping at all.

If the ferules are so thin, they easily deform under pressure then there should be no good contact inside the ferrule.

[smile]

Now knipex own video shows this crimp quality or the lack of it:

BTW ferrules usually are not crimped as a one flat piece.

This make me wonder if they work OK in spring loaded terminals like wago 221? The uneven surface of the ferrule, what about good contact and small resistance, big surface area??

[Fraser]

Regarding the video I referenced showing poor tradecraft in making power crimp terminations.... credit to the video blogger, in response to my comments and direction to NASA guidance on the topic, he has pulled the video.

Dangar Marine is normally a fun channel to watch and he is a responsible chap. He replied in a positive manner to my comments on the video. I wish more video bloggers did the same when they were obviously showing poor tradecraft. In this case the video was based on poor advice he had been given by his audience concerning a previous video on making battery leads.

It just shows how misinformation can spread. Just because it's on the internet or someone tells you something, does not make it true. Research, research, research 

At least this particular misleading video has now been taken down.

For those who did not see it, the presenter showed how to terminate high current battery cables for use in maritime vessels. On advice from his viewing community he applied copious amounts of solder to the copper cable using a blow torch, apparently to prevent corrosion.  The copper conductors spread as the heat burned the insulation and solder filled the gaps between them. He then tried the same task using a 50W Weller type electronics soldering iron with a fine electronics tip fitted. Not surprisingly it created a useless blobby mess on the cable conductors. He was trying to show how hard it is to tin such large cables using a 'normal' soldering iron.

We were then treated to a lesson in how to make your own crimp lugs using lengths of copper tube that had been partially flattened in a vice and drilled to form a lug. The hollow oversize end was then slipped over the solder tinned cable ends and a hydraulic crimping tool used to compress the tube. The result was a DIY crimp that had wings on each side as the crimp die was too small for the tube diameter !

I commented that such a termination may be fine as an emergency bush engineering solution but it had no place on a marine vessel as its failure could strand the vessel. The idea of using a plain unplated copper DIY lug termination on a heavily solder plated multi core cable was abhorrent to me and a disaster waiting to happen. There was so much solder on the cable that The crimp would be compressing down onto a combination of copper and soft electronics solder. The solder would flow over time due to the pressure on it and the termination would fail. The cable was to be used in a 'tinny' Aluminium hulled boat. You can imagine what a 'live' high current sourcing 12V cable could do if it broke loose and started shorting to the Aluminium hull  Even if not so serious, just the heating of a poor termination and its resultant poor conduction under load could disable a vessel.

The author of the video obviously did his reaseach (a bit late) and realised he had been given poor advice.

Fraser